The invention relates to electronic scales for weighing of heavy duty trucks, and specifically to scales with a new and improved weighbridge design, and to a new and improved method for constructing truck scales.
Heavy duty truck scales are well known in the art; numerous designs are available on the market. Current truck scales use a weighbridge, which is supported on a plurality of load cells. The width of the weighbridge must be about 10' (3 m) for regular over-the-road trucks, and the length of the weighbridge must be about 30' (9 m) for simple trucks, such as dump trucks, and nearly 100' (30 m) for the longest tractor trailer rigs.
The large size of a weighbridge for truck scales makes it difficult to transport them from a manufacturing shop to the site of a scale installation, so many designs have been developed to minimize the transportation problem.
One solution involves assembling a large steel weighbridge on site, more or less from scratch. An alternative is to pour a large concrete weighbridge on site. These types of weighbridges are very time consuming and expensive to build, and they generally can not be moved to a different location later on.
Another solution is to assemble the deck from a number of wide, but short and relatively light steel modules, each supported on four load cells, for instance as disclosed in U.S. Pat. No. 4,266,624. The cost for a scale based on this design is high, both because a large number of load cells are required, and because the modules are made of steel.
A third solution involves the use of two beams placed side by side on cross-beams, which in turn are supported by load cells, for instance as described in U.S. Pat. Nos. 3,770,068 and 4,887,678. This design can be used with concrete beams, and has had enjoyed considerable success, but the cross beams add to the cost and complexity of a scale installation.